This invention relates generally to gas turbine engines and more particularly to gas turbine engine components formed in part from high temperature foil materials.
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. In a turbofan engine, which typically includes a fan placed at the front of the core engine, a high pressure turbine powers the compressor of the core engine. A low pressure turbine is disposed downstream from the high pressure turbine for powering the fan. Each turbine stage commonly includes a stationary turbine nozzle followed in turn by a turbine rotor.
Gas turbine engine hot section components, in particular the high pressure turbine section components, operate at extremely high temperatures and need to be cooled to have acceptable longevity. The tips of high pressure turbine (HPT) blades in particular are susceptible to high temperatures. The cooling is typically provided by extracting relatively cool air from an upstream location of the engine and routing the cooling air to components where it is needed. Conventionally the components to be cooled are hollow and have provisions for receiving and distributing the cooling air by various methods, for example the components may be film cooled by providing a plurality of passages which eject a blanket of cooling air over the surface of the component, or the components may be convectively cooled by causing the air to flow through various internal passages. Convection cooling can be implemented by using a very thin wall spaced apart from a substrate to provide a flow channel for cooling air. Very thin walls cast from conventional superalloys require increased cooling air flow to ensure the longevity of the walls, which reduces the overall efficiency of the engine cycle. Materials having better high temperature properties than conventional superalloys are available. However, their increased density and cost relative to conventional superalloys discourages their use for the manufacture of complete gas turbine components.
Accordingly, there is a need for gas turbine engine components able to withstand higher temperatures without excessive use of cooling air.